• Question: veins carry deoxygenated blood and yet human beings are injected in the vein

    Asked by abrb279 to Cheryl, Christina, Daniel, George, Ivy on 26 Jan 2017.
    • Photo: Cheryl Andisi

      Cheryl Andisi answered on 26 Jan 2017:

      I suspect this is a question that @Christina might have a better response to.
      I think that intravenous injections ie injections in the veins are given because veins carry oxygenated blood to larger vessel, usually under lower pressure. If administration a drug damages a vein, the effects will be smaller. Arteries on the other hand supply oxygenated blood to smaller capillaries, and since these originate from the heart, are usually under high pressure. Damage of the artery is thus more likely to lead to negative effects covering larger areas.
      The ultimate reason why anyone would need an IV injection is because they need that medication to reach all parts of their bodies ie via blood. Whether oxygenated or deoxygenated, blood will continue going through the body and reach all tissues and cells thus carry out its desired effect.

    • Photo: Christina Obiero

      Christina Obiero answered on 26 Jan 2017:

      Hi abrb279, you are right about veins carrying deoxygenated blood from the different parts of the body. This blood circulates back to the right side of the heart where it is pumped to the lungs for oxygenation. Oxygenated blood then circulates to the left side of the heart and pumped to the rest of the body.
      Administration of medicine or fluids is done through the venous access because the medication/fluid need to be circulated by the blood to the parts of the body for absorption. Venous blood will transport the medication to the heart, lungs then heart and during circulation, the medicine gets absorbed in the body and is transported to the organs where it needs to act. It is not necessary to give medication in oxygenated blood via arteries but this can be done in case the veins cannot be easily found e.g. in a patient who has stayed in hospital for long and has had most of the visible and accessible veins injected.

      It is also easier to inject medicine through the vein because veins are easier to see, feel and find than arteries. Also, arteries have a stronger wall hence they tend to pulsate and if they are pricked/injected, they can easily get damaged.

      Veins too tend to thicken (sclerose) after they have been injected/pricked and used to give medication over long periods of time.